Signal Grounding; Wire Shield Grounding - Honeywell ControlEdge 900 platform Hardware Planning And Installation Manual

Signal grounding

The shield for each analog input and analog output should be
grounded at the grounding bar at the top or bottom of each rack as
indicated in the following figure. For low-frequency noise rejection,
I/O wiring shields should be grounded only at the ControlEdge 900
Controller end.
Figure 5-19: Wire-signal Grounding for low-frequency noise rejection
For high-frequency noise rejection, shields should be grounded at the
ControlEdge 900 Controller and at the field device. If the ground
voltage potential at the field device is different from that at the
ControlEdge 900 Controller, a DC isolation capacitor (1nf/2000V)
should be used between the shield and the grounding bar on the rack.
Figure 5-20: Wire-signal Grounding for high-frequency noise rejection

Wire shield grounding

Aluminum grounding bars for I/O wiring are available as options.
When selected for use, they are fastened to the top and/or bottom of
each rack, as indicated in the following figure. To enable connection
of multiple ground wires with a single screw, the wires can be twisted
together and secured with a wire lug.
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